Problem: Which of these numbers is composite? ${5,\ 13,\ 19,\ 38,\ 73}$
A composite number is a number that has more than two factors (including 1 and itself). 5, 13, 19, and 73 each have only two factors. The factors of 38 are 1, 2, 19, and 38. Thus, 38 is the composite number.